1. Field of the Invention
The present invention relates to a pressure cylinder structure, and more particularly to a double-force type pressure cylinder structure.
2. Description of the Related Art
A conventional clamping device, such as a vice, is used for clamping a workpiece to be worked by a working machine such as a milling machine. However, the vice is operated manually so that the clamping and holding effect provided by the vice on the workpiece is not sufficient and efficient, thereby greatly affecting the working efficiency of the working machine.
In accordance with one aspect of the present invention, there is provided a double-force type pressure cylinder structure comprising:
a pressurizing cylinder base defining a radial through hole having a first side threadedly provided with a liquid inlet port having a distal end for receiving a first ball, thereby forming a first check valve, and having a second side threadedly provided with a liquid outlet port having a distal end for receiving a second ball, thereby forming a second check valve, the pressure cylinder base having a central portion defining a pressurizing cylinder chamber for receiving a piston rod, the pressurizing cylinder chamber having a top defining a screw hole for receiving a sealing bushing, a support bushing screwed into the screw hole for securing the sealing bushing and for supporting the piston rod which is sealed by the sealing bushing;
a gas cylinder secured on the pressurizing cylinder base and containing a piston therein, the piston having a bottom defining an inner annular hole for receiving a flange disk, the flange disk having a central portion screwed on one end of the piston rod, a spring having a first end secured on the flange disk and a second end secured on an end face of the pressurizing cylinder base so that the piston is pushed upward by the spring, a main air drain hole longitudinally defined in a wall of the gas cylinder and extending into a bottom of the gas cylinder, a direction change air drain hole longitudinally defined in the wall of the gas cylinder and extending into a mediate portion of the gas cylinder; and
a top cap secured on the gas cylinder by bolts and having a central portion defining a through stepped hole, the stepped hole provided with an inner flange, the inner flange having a bottom for receiving a lower piston base and a top for receiving an upper piston base which is screwed by bolts, the upper piston base defining an inner cylinder chamber, the lower piston base having an upper portion defining a concave annular hole for receiving an upper valve plug and a lower valve plug, and having a lower portion for receiving a spline which defines a plurality of radially arranged slots, an O-ring mounted on a distal end of the spline, a direction change piston slidably mounted in the inner cylinder chamber of the upper piston base and having an axle extending into the upper valve plug and abutting an end face of the spline, a threaded post extending through a block ring, through the spline and screwed into the axle of the direction change piston so that the spline is integrally coupled with the direction change piston while the block ring closes the slots of the spline.
Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings.